chrismuzz Posted June 13, 2012 Share Posted June 13, 2012 Just thinking to myself this morning and it made me wonder..... I have a 500w head with a minimum load of 4 ohms. If I run it through a single 8 ohm cab I am getting 300w.... So... Even though if I was to use one 4 ohm head I would have 500w..... Does this mean running two 8 ohm cabs would be THE EQUIVALENT of a 600w rig? (told you it was a stupid one ) Quote Link to comment Share on other sites More sharing options...
xgsjx Posted June 13, 2012 Share Posted June 13, 2012 (edited) Your amp's max wattage output is 500w, therefore 2 8 ohm cabs would still get a maximum draw of 500w (250w each regardless of their wattage). Does that help? Edit: If you're using 2 heads, each going into it's own cab then you'll be feeding each @ 350w. So a 700w rig. Edited June 13, 2012 by xgsjx Quote Link to comment Share on other sites More sharing options...
chrismuzz Posted June 13, 2012 Author Share Posted June 13, 2012 Thanks man! It was just bugging me really I wondered why I wasn't just getting 250w from using 1 cab and thought it was either an estimation, or measured by the total output or some crap like that. With my setup I think two heads would be complete overkill unless I was running 1 clean and 1 effected... But why do that when practically all of my effects have a clean blend? Quote Link to comment Share on other sites More sharing options...
xgsjx Posted June 13, 2012 Share Posted June 13, 2012 Also, if you did need clean blend, then your fx loop provides that. Quote Link to comment Share on other sites More sharing options...
subsong Posted June 15, 2012 Share Posted June 15, 2012 Your amp is rated to give you a certain amount of power, based on pushing it into a load that gives a certain amount of electrical resistance (measured in ohms). Typically bass amp power ratings are based on a 4 ohm resistance. If you double the load you don't get half the power, you usually something between half and two thirds of the power, it depends on the amp. More resistance is fine, it just means less power. Still, it's usually enough. Be careful of giving it too little resistance though. So never plug 2 4ohm cabs into your amp. That'll make a 2 ohm load, which isn't enough resistance, and your output transformer will overheat and maybe be damaged. Some high end bass amps do go down to 2 ohms, not many though. Quote Link to comment Share on other sites More sharing options...
ThomBassmonkey Posted June 15, 2012 Share Posted June 15, 2012 IIRC in a completely hypothetical world, a 500w amp at 4ohms would run 250w at 8ohms. In the real world though it's not that simple. I can't remember why though. Quote Link to comment Share on other sites More sharing options...
chrismuzz Posted June 15, 2012 Author Share Posted June 15, 2012 [quote name='ThomBassmonkey' timestamp='1339803205' post='1694859'] IIRC in a completely hypothetical world, a 500w amp at 4ohms would run 250w at 8ohms. In the real world though it's not that simple. I can't remember why though. [/quote] Yeah it's weird! Because surely when you have two cabs they both 'get' 250w each Quote Link to comment Share on other sites More sharing options...
ThomBassmonkey Posted June 16, 2012 Share Posted June 16, 2012 It's confusing because actually the 8Ohm wattage is nearer to what the wattage would be in a perfect world. Rather than it being "a 500w amp at 4 ohms should put out 250w in 8 ohms but actually puts out 300", it's a case of "an amp that puts out 300w in 8 ohm mode should put out 600w in 4 ohms but because the amp's not efficient enough, it puts out 500w" if that makes sense. Quote Link to comment Share on other sites More sharing options...
flyfisher Posted June 16, 2012 Share Posted June 16, 2012 [quote name='ThomBassmonkey' timestamp='1339803205' post='1694859'] IIRC in a completely hypothetical world, a 500w amp at 4ohms would run 250w at 8ohms. In the real world though it's not that simple. I can't remember why though. [/quote] Because that hypothetical world example assumes the amp's efficiency is linear whereas in the real world it isn't, so the comparison isn't valid - apples and pears and all that. Quote Link to comment Share on other sites More sharing options...
flyfisher Posted June 16, 2012 Share Posted June 16, 2012 [quote name='chrismuzz' timestamp='1339804514' post='1694873'] Yeah it's weird! Because surely when you have two cabs they both 'get' 250w each [/quote] They both 'get' 250W each because, together, they present a 4 ohm load to the amp so it 'sends out' 500W and that 500W is split evenly between the two cabs because they are both the same. Quote Link to comment Share on other sites More sharing options...
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